This chromosome fragility involves the generation of chromosome/chromatid gaps or breaks, or the high frequency loss of one or both copies of the affected gene. Other repeat diseases, like Fragile X Syndrome (FXS) have been shown to have chromosome fragility. This has not been previously studied in FA. This research shows that the region of chromosome 9 that contains the FXN locus is intrinsically prone to breakage in vivo even in control cells. However, like FXS alleles, FRDA alleles show significantly elevated levels of chromosome abnormalities in the presence of an ATM inhibitor, consistent with the formation of a fragile site.